The present disclosure generally relates to enhancing images from electronic displays, and specifically to varying a focal length of optics with a compact design to enhance comfortable viewing experience in head mounted displays.
Virtual reality (VR) headset can be used to simulate virtual environments. For example, stereoscopic images can be displayed on an electronic display inside the headset to simulate the illusion of depth and head tracking sensors can be used to estimate what portion of the virtual environment is being viewed by the user. Such a simulation, however, can cause visual fatigue and nausea resulting from an inability of existing headsets to correctly render or otherwise compensate for vergence and accommodation conflicts. Augmented Reality (AR) headsets display a virtual image overlapping with the real world. To create comfortable viewing experience, the virtual image generated by the AR headsets needs to be displayed at the right distance for the eye accommodations of the real world objects at different time.